Date: Sun, 30 Dec 2018 23:18:14 +0100 From: =?UTF-8?B?VMSzbA==?= Coosemans <tijl@FreeBSD.org> To: Andrea Venturoli <ml@netfence.it> Cc: freebsd-x11@freebsd.org Subject: Re: Radeon HD 4250: screen going blank every few seconds Message-ID: <20181230231814.4bf4cbff@kalimero.tijl.coosemans.org> In-Reply-To: <20181230224607.1feb9cad@kalimero.tijl.coosemans.org> References: <4560f9e2-efcf-a1f5-728c-c26fcec34353@netfence.it> <20181230224607.1feb9cad@kalimero.tijl.coosemans.org>
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On Sun, 30 Dec 2018 22:46:07 +0100 Tijl Coosemans <tijl@FreeBSD.org> wrote: > On Sun, 30 Dec 2018 20:29:49 +0100 Andrea Venturoli <ml@netfence.it> wrote: >> I've got a desktop which used a Radeon HD 4200 with no troubles: I was >> using a 1920x1200 monitor on the DVI port and occasionally a second one >> on the VGA port; this system had no HDMI port. >> >> >> >> Now I changed mainboard with an Asus M5A88-V Evo (latest BIOS >> installed), which features a Radeon HD 4250 and I'm getting some troubles. >> >> Focusing only on one monitor, it works fine if connected to the VGA >> port, but I'd like to avoid this setup because: >> a) begin analogic, it shows some background noise; >> b) it won't allow me to use the second monitor. >> >> So I'd like to use either the HDMI or the DVI port, but in this case: >> _ the system start fine and is stable as long as BIOS resolution is used; >> _ as soon as I "service kld start" and the resolution switchs to >> 1920x1200 the screen starts flickering: every 1-2 seconds the image goes >> black (the monitor displaying "DVI Input" or "HDMI Input" as if a new >> signal was detected) and gets back to normal in another 1-2 seconds; >> _ once XOrg is up and running the problem does NOT disappear. >> >> As I suspected an hardware problem, I tried booting Knoppix: initially I >> get the same behaviour (works fine, then starts flickering once the >> resolution is increased); however, after XOrg is running the problem stops. >> So, either it isn't an hardware problem or there is a workaround. >> >> Also worth mentioning: >> _ if I decrease the resolution to 1920x1080 everything is ok, of course >> apart seeing two black areas on the top and bottom of my screen :( >> _ while keeping full resolution, attaching the second monitor on the VGA >> port *and enabling it* will reduce the flickering from every 1-2 seconds >> to every 5-10 seconds. >> >> >> >> >> So I'm asking for some help, since either using the VGA port or >> decreasing the resolution is not a workaround I'm eager to adopt; is >> there anything that can be done? Some sysctl? Some BIOS settings? Some >> xorg.conf tweak? Some update to test? >> >> I tried and searched if this was a known (or at least previously seen) >> problem, but came up empty. >> Even some pointer to documentation/knowledge base would help... > > Try running "sysctl compat.linuxkpi.hw_i2c=0". This seems to be a loader tunable so you'll have to add compat.linuxkpi.hw_i2c=0 to /boot/loader.conf and reboot.
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